REVIEW 3 major objections 5 minor 10 references
A Quantum Guitar
T0 review · 3 major / 5 minor · reviewed 2026-08-05 · deepseek-v4-flash
Pith's one-line read A guitar can be turned into a live-performance quantum instrument by attaching a qubit to each playable string state and controlling it with foot pedals.
desk verdict A fun, honest instrument-build report, not a physics paper, and its 'quantise all strings' claim is contradicted by the single-qubit implementation. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The qubit-per-string mapping is the load-bearing idea: each playable state of a guitar string is assigned a qubit, and Actias sonifies and displays that qubit. Rotations of the qubit are driven by two Boss EV-1-WL MIDI expression pedals, with an internal switch covering the third rotation; measurement is triggered by a Boss FS-6 foot switch in momentary mode; and Boss FV500 volume pedals independently control the classical and quantum signal levels. A Fernandes sustainer pickup (or, alternatively, long delay/reverb) lets notes ring continuously enough for the quantum sound. The foot-based control scheme is what keeps the musician's hands free for ordinary guitar playing.
What would settle it
Log MIDI events and Actias state through a full live set under the paper's tech-rider conditions: a single mid-performance preset loss or a missed note-off while bending a string would refute the reliability claim.
Extended reading notes
Core claim
The central claim is that a guitar can become a working quantum musical instrument by mapping each playable state of a string to a qubit and sonifying that qubit with Moth's Actias quantum synth. The guitar retains all its classical sound and playability, while foot-controlled MIDI pedals rotate the qubit, a foot switch performs measurements, and two volume pedals let the musician blend continuously between pure classical guitar and quantum sound. Because all quantum controls use the feet, one seated musician can operate the full instrument. The author reports multiple live performances, including industrial music with Black Tish and a sonified Bell-pair performance with grand piano, and use
Load-bearing premise
The instrument's 'battle-ready' claim rests on the stability of the Actias quantum synth software and the MIDI pickup's tracking; the paper itself admits these sometimes lose presets or need reconnection, so if they fail on stage the central claim collapses.
Editorial extensions
If this is right
- The same hands-free, foot-controlled architecture can be copied to create Quantum Violin, Quantum Wind Instrument, and Quantum Percussion without sacrificing classical playability.
- Smooth continuous transitions between quantum and classical sound become a live performance tool, useful for building tension or shifting texture mid-piece.
- A single seated musician can play the full instrument because quantum controls require no hands, opening the way for one-person quantum ensembles.
- The instrument has already been used in industrial music, with Black Tish recording an album entirely with it, and in a sonified Bell-pair composition with grand piano.
- Planned pairings with cathedral organ require only the listed tech rider, suggesting the instrument can slot into existing performance logistics.
Reading between the lines
- Extension: If the foot-controlled qubit interface proves stable across repeated live uses, the same controller scheme is a reusable template for hands-free quantum control of any instrument, not just guitar.
- Extension: The paper's own troubleshooting list—Actias occasionally losing its preset, MIDI reconnection hiccups, and one-laptop unreliability—marks the boundary between a proven prototype and a fully dependable stage instrument; stabilising those is the direct next step.
- Extension: The 'quantisation' here is a musical and control mapping rather than a physical quantisation of the string's vibrations, so the instrument's value is primarily as a new expressive interface and outreach tool, not as a test of quantum physics.
- Extension: The paper's suggestion to add X-measurements as primitive operations, rather than requiring a rotation first, is a concrete, testable improvement that would likely make the instrument significantly easier to play.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper describes the 'Quantum Guitar', an electric guitar augmented with a MIDI pickup, a sustainer pickup, foot-controlled expression pedals, a foot switch, and Moth's Actias quantum synthesizer, which sonifies a single qubit. The author claims that by associating a qubit to each playable state of a guitar string, the instrument realizes a 'quantisation of all strings', and that the instrument has proven versatile and reliable in live performances, including with the industrial band Black Tish. The paper is a non-technical system description, containing no mathematical derivation, no audio analysis, and no reproducible data, but includes a troubleshooting section and links to a demo video and performance pages.
Significance. If realized as described, the instrument is a creative contribution to quantum music: it enables a single musician to manipulate a qubit hands-free using foot pedals while maintaining full classical guitar playability, and it offers a continuous quantum-classical sound transition. The explicit acknowledgment of hardware and software limitations is a positive feature. However, the scientific significance of the paper is limited by the absence of technical specifications and systematic evaluation, and the central conceptual claim of per-string quantisation is not implemented in the presented hardware.
major comments (3)
- [Abstract and §2 vs. §3, Figs. 5–6] The abstract and §2 claim that 'by associating a qubit to each of its playable states we obtain a quantum wave, i.e. quantisation of a guitar by means of quantising its strings.' Yet the implementation in §3 uses exactly one qubit in Actias, controlled by two foot pedals and a foot switch, and the text explicitly states 'we are working with a single qubit'. There is no per-string or per-playable-state allocation of qubits in the hardware or software. If the intended claim is that the guitar is an interface to a single qubit, the 'quantising all strings' language is unsupported; if the intended claim is per-string quantisation, the implementation does not realize it. This mismatch undermines the headline conceptual contribution.
- [§1 and §4] The abstract and §1 describe the instrument as 'very uniquely versatile and reliable' and a 'battle-ready axe', but §4 lists several reliability failures: Actias 'sometimes looses its preset', unplugging and replugging 'sometimes requires deleting an external midi device', and 'Having everything on one laptop doesn't function reliably'. The evidence for reliability is anecdotal, based on the author's own performances and a YouTube link, with no systematic test logs, failure statistics, or independent evaluation. The reliability claim should be either tempered to reflect the troubleshooting data or supported by a more rigorous evaluation protocol.
- [§3 (and throughout)] The paper does not specify whether the 'qubit' in Moth's Actias is implemented on actual quantum hardware or simulated on a classical computer. The scientific content of the 'quantum guitar' depends on this distinction. If the qubit is simulated, the paper should explain what genuine quantum feature (e.g., superposition or interference) is retained and whether the sound synthesis itself is quantum or merely controlled by a quantum process. Without this clarification, the term 'quantum' in the central claim is ambiguous.
minor comments (5)
- [§7 title] The section title 'Relases' should be 'Releases'.
- [§4] 'looses its preset' should be 'loses its preset'.
- [Introduction] 'electro-accoustic' should be 'electroacoustic'.
- [Acknowledgements] 'at and TUM's International Quantum Forum' should be 'at TUM's International Quantum Forum' or 'at the TUM International Quantum Forum'.
- [§3 and Fig. 6] The discussion of the 'third qubit rotation' and the statement that 'green' is 'not supposed to change the state' is confusing, especially since Figure 6's caption says 'green' and 'orange' cannot be used independently. Please rewrite for clarity and ensure the colors are legible in the figure.
Circularity Check
No circular derivation; the paper is a construction report with self-referential performance claims, not a prediction-equals-input chain.
full rationale
The paper contains no mathematical derivation chain in which an output is shown to equal an input. The central claim in the Abstract and Section 2 ('a guitar string represents a wave, and by associating a qubit to each of its playable states we get a quantum wave') is a design principle, not a derived result; it states the intended construction rather than predicting a quantity from fitted inputs. The instrument's value is supported by the author's own live performances and by self-citations to prior compositions ([1], [8], [9]), but these are rhetorical and descriptive, not load-bearing derivations: no cited theorem is invoked to forbid alternatives or to force a conclusion. Section 4 explicitly admits reliability limitations ('Actias sometimes looses its preset', 'Unplugging and replugging sometimes requires deleting an external midi device', 'Having everything on one laptop doesn't function reliably'), which honestly undermines the 'reliable instrument' claim but is not circular reasoning. The apparent mismatch between the 'qubit to each playable state' language and the single-qubit Actias implementation is an internal consistency issue, not a circularity of the derivation-equals-input type. Therefore no significant circularity is present.
Assumptions & free parameters
assumptions (2)
- domain assumption A qubit can be associated with each playable state of a guitar string to produce a 'quantum wave'.
- domain assumption Moth's Actias software reliably sonifies qubit states and accepts MIDI control for rotations and measurements.
Cite this review
Pith. "Pith review of A Quantum Guitar." pith.science (2026). https://pith.science/paper/H2F5LXEA
@misc{pith2026250904526,
author = {Pith},
title = {Pith review of: A Quantum Guitar},
year = {2026},
howpublished = {\url{https://pith.science/paper/H2F5LXEA}},
note = {Machine review of arXiv:2509.04526}
}
read the original abstract
A guitar string represents a wave, and by associating a qubit to each of its playable states we get a quantum wave. This is the principle behind our Quantum Guitar: `quantising all strings of a guitar'. In order to achieve this quantisation, we couple a guitar with Moth's Actias quantum synth, and for qubit manipulations including measurements the musician uses foot controllers - hence using all four limbs like a drummer. Our Quantum Guitar also allows for smooth continuous transition from `quantum' to `classical' sound, and vice versa. We have used our Quantum Guitar in several live performances in a variety of venues, playing a number different musical styles, hence demonstrating that it is a very uniquely versatile and reliable instrument. For example, in some performances Quantum Guitar was used in industrial music, by the band Black Tish, who are currently recording an album with it. In other performances Quantum Guitar represented a qubit within a sonified Bell-pair under measurement, the other qubit being mentally realised with a Grand Piano. Classical-quantum and quantum-classical transitions prove particularly useful in musical performance. A link to a demo video of Quantum Guitar is provided.
Figures
Figures from the paper (2 more)
Reference graph
Works this paper leans on
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[1]
A quantum natural language processing approach to musical intelligence
Eduardo Reck Miranda, Richie Yeung, Anna Pearson, Konstantinos Meichanetzidis, and Bob Coecke. A quantum natural language processing approach to musical intelligence. In Quantum Computer Music: Foundations, Methods and Advanced Concepts , pages 313--356. Springer, 2022
work page 2022
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[2]
Eduardo Reck Miranda. Quantum Computer Music. Foundations, Methods and Advanced Concepts . Springer, 2022
work page 2022
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[3]
S. Alexander Reed. Assimilate: a critical history of industrial music . Oxford University Press, 2013
work page 2013
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[4]
Bodies, Noise and Power in Industrial Music
Jason Whittaker and Elizabeth Potter. Bodies, Noise and Power in Industrial Music . Springer, 2022
work page 2022
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[5]
The Big Takeover, 2023. bigtakeover.com/recordings/black-tish-throbbing-flip-out-blindsight-records https://bigtakeover.com/recordings/black-tish-throbbing-flip-out-blindsight-records
work page 2023
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[6]
Your EDM, 2023. www.youredm.com/2023/10/04/new-artist-spotlight-sort-of-meet-black-tish-the-pioneering-industrial-band-that-released-their-work-35-years-late/ https://www.youredm.com/2023/10/04/new-artist-spotlight-sort-of-meet-black-tish-the-pioneering-industrial-band-that-released-their-work-35-years-late/
work page 2023
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[7]
Q1synth: a quantum computer musical instrument
Eduardo Reck Miranda, Peter Thomas, and Paulo Vitor Itabora \' . Q1synth: a quantum computer musical instrument. Applied Sciences , 13(4):2386, 2023
work page 2023
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[8]
R.-B. Abdyssagin and B. Coecke. Quantum concept music score from quantum picturalism: Musical incarnation of a B ell-pair under measurements. In 3rd International Symposium on Quantum Computing and Musical Creativity , 2025
work page 2025
Show all 10 references
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[9]
B. Coecke. Basic zx-calculus for students and professionals. arXiv preprint arXiv:2303.03163 , 2023
2023 arXiv
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[10]
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Reviewed August 5, 2026 · model on record in the stance chip above.
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